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Cervical Cancer Diagnosis

Abnormal Pap Test Results

An abnormal Pap test result does not mean you have cervical cancer. It indicates some degree of cellular change in the cells that cover the surface (lining or epithelium) of the cervix.

While the Pap test cannot reliably confirm a herpes infection, it can indicate infection with HPV.

Pap test classifications include:

  • Benign (noncancerous) cellular changes. These result from inflammation caused by a number of things, including diaphragm use or infection with trichomonas, a sexually transmitted vaginal infection.

  • Atypical squamous cells of undetermined significance, or ASCUS. These cellular changes appear abnormal for unknown reasons. It isn't possible to determine if the abnormality is caused by inflammation, infection or by precancerous changes. These types of cellular changes usually return to normal without intervention or after treatment of an infection. Follow-up for this Pap test result is usually a repeat Pap test in three to six months.

  • Squamous intraepithelial lesion (SIL). This change is considered precancerous. SIL changes are divided into two categories: low-grade SIL and high-grade SIL.

    • Low-grade SIL refers to early changes in the size, shape and number of cells on the surface of the cervix. Most of these lesions return to normal on their own without treatment. Others, however, may continue to grow or become increasingly abnormal in other ways and develop into a high-grade lesion.

      Other terms for low-grade SIL are mild dysplasia or cervical intraepithelial neoplasia 1 (CIN 1). According to the National Cancer Institute, these precancerous changes occur most often in women ages 25 to 35, but can appear in other age groups, as well.

      Generally, your health care professional will recommend a diagnostic test as a follow-up if your test is categorized as low-grade SIL/CIN I, including colposcopy and biopsy.

    • High-grade SIL. Cells in this category look very different from normal cells and are less likely to return to normal without treatment and more likely to develop into cancer. These abnormal cellular changes are still confined to the surface of the cervix only and still are considered precancerous changes. High-grade SIL is most common in women age 30 to 40, but can occur in other age groups, as well.

      Other terms for high-grade SIL are moderate or severe dysplasia (CIN 2 or CIN 3) carcinoma in situ.

      Follow up for high-grade SIL/CIN 2 or CIN 3 involves additional procedures, including biopsy, to determine the degree of abnormality and rule out invasive cancer.

In some cases, a Pap test may report that abnormal cells are present in a sample when, in fact, the cells in question are normal. This type of abnormal report is known as a false positive.

When a Pap test fails to detect an existing abnormality, the result is called a "false negative." Even under the best of conditions, there is always a small, but irreducible, false negative rate. Several factors may contribute to a false negative Pap test:

  • When irregular cells are located high in the cervical canal they are difficult to access under normal Pap test procedures.

  • Menstrual blood and inflammatory cells can mask abnormal cells; these cells would not be visible to the cytotechnologist.

  • An inadequate sample - not enough cells were collected during the Pap test.

  • Human error, in which the person reviewing the slide misinterpreted abnormal cells as normal.